1. Field of the Invention
The present invention relates to an electronic calculator with an alterable keyboard and more particularly to an electronic desk-top calculator with a manually changeable keyboard, the size of which may vary.
2. Description of the Prior Art
Prior art keyboard modules and similar articles generally must correspond nearly exactly in size with the apertures into which they are inserted. In addition, for removal such modules and the associated devices into which they are inserted are so constructed that a plurality of releasing members must be actuated or the associated devices must be partially disassembled or lifted or turned over to permit access to the module.
A signal switching system and control keyboard suitable for use therein is disclosed in Carr et al., U.S. Pat. No. 3,394,368. Carr et al. describes a control keyboard containing a replaceable reversible magazine of different legend-bearing plates each actuable automatically to a visible position to identify the functions of associated control switches when a corresponding function switch is operated. Coding members on the magazine and on the plates provide control signals indicating which magazine, in which orientation, is in the keyboard and which plate is actuated to visible position at any time, and these control signals are used to control selection of the data displayed under control of the keyboard.
A key operated switch is disclosed in Feder, U.S. Pat. No. 3,663,774, including a system which uses a plug-in type printed circuit module and associated circuitry for sending a signal representing a binary coded decimal digit. There is described an actuation cylinder having a conductive contact bar mounted therein and a key slot through the center. A circuit means is provided for connecting the actuation cylinder bar and external circuitry when the actuation cylinder is rotated. The actuation switch is insertable into a magazine.
An expandable keyboard for electronic pocket calculators and the like is disclosed in Margolin, U.S. Pat. No. 3,940,758. Margolin describes an expandable keyboard for a pocket type calculator. The keyboard is made in a modular form and electrically interconnects and forms a keyboard much larger than that of a familiar pocket calculator. The keyboard portions are hinged together normally forming a stack, which occupies along with the display and the electronics, a space about as large as a conventional pocket calculator. The portions hinge or snap fit in a side by side relationship with a main portion conveniently affixed to a housing for the electronics for the various functions. Electrical interconnection between the side portions of the modular or folding keyboard arrangement is achieved at the edges of the portions by means of arrays of electrical interfaces exposed at the mating edges for interconnection.